1. Field of the Invention
The present invention relates to a continuous roll sheet holding apparatus and a printing apparatus that includes the same.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2002-46902 discusses a roll sheet holding apparatus that is applied to a printing apparatus and fitted to an end of a sheet wound in a roll shape to rotatably hold the sheet.
The roll sheet holding apparatus includes, to fit holding flanges to both ends of the roll sheet and rotatably hold the roll sheet, a driven gear to which a driving force is transmitted, and a transmission member that transmits a rotational force of the driven gear to one of the holding flanges. The roll sheet holding apparatus further includes a rotary shaft rotated by a driving force from a driving source of the roll sheet holding apparatus in a direction parallel to an axial direction of the roll sheet, and a driving force transmission unit including a driving force transmission gear slidable in an axial direction of the rotary shaft. The driving force transmission gear can stop at a predetermined position in the axial direction of the rotary shaft, and engages with the driven gear of the holding flange to transmit the driving force.
A roll sheet housing unit includes engaged portions to fix the respective holding flanges fitted to both ends of the roll sheet. The holding flange includes an engaging portion that can engage with the engaged portion.
As compared with a conventional method for inserting a holding shaft into a core of a roll sheet to fix the roll sheet, fitting of a long holding shaft to the roll sheet is unnecessary. Thus, this configuration can improve roll sheet replacement work.
In a printing apparatus, driving is transmitted to rotate and feed the roll sheet to a printing unit. Consequently, in loading positions of the roll sheet and the holding flanges, position regulation is usually imposed with respect to a winding direction. Also in loading of the roll sheet in the roll sheet housing unit, a phase occurs between the winding direction and the loading direction of the roll sheet.
When the loading positions of the holding flanges are determined to be incorrect with respect to the winding direction after the holding flanges have been fitted to the roll sheet, the holding flanges must be removed from the roll sheet to be fitted to correct positions again.
When the holding flange that includes the driving force transmission unit is not fitted to a determined end side of the roll sheet but loaded in the roll sheet housing unit with respect to the winding direction of the roll sheet, the winding direction of the roll sheet is reversed. When the roll sheet is fed to the printing unit while the winding direction is reverse, ink is discharged to a rear surface of the roll sheet. The ink is thus insufficiently absorbed by the sheet, and the roll sheet is conveyed to a conveyance path on the downstream side of the printing unit. Consequently, the ink may be transferred to a conveyance unit, staining a sheet to be conveyed next.
Conventionally, the driving force transmission unit is connected when the roll sheet is loaded in the roll sheet housing unit. The loading directions of the holding flanges with respect to the roll sheet housing unit are thus predetermined. Consequently, the operation must be performed while checking engaging positions of the holding flanges and an engaged position of the roll sheet, making the loading difficult.